Frictionally driven switch



Jan. 9, 1940. H. E. METCALF 2,186,765

FRICTIONALLY DRIVEN SWITCH Filed Jan. 17, 1958 INVENTOR HERBERT E. METCALF GIMM- ATTORNEYS.

Patented Jan. 9, 1940 UNITED STATES PATENT OFFICE FRICTIONALLY DRIVEN SWITCH fornia Application January 1'7, 1938, Serial No. 185,255

5 Claims.

My invention relates to frictionally driven switches and more particularly to switches which will open and close circuits in accordance with the rotation of a shaft irrespective of the amount of rotation of the shaft in either direction.

Among the objects of my invention are: To provide a simple and easily assembled frictional switch; to provide a switch which will indicate direction of rotation of a shaft; to provide a switch having a single resilient element therein, simultaneously energizing a friction clutch and supplying contact pressure.

Other objects of my invention will be apparent or will be specifically pointed out in the description forming a part of this specification, but I do not limit myself to the embodiment of. the invention herein described, as various forms may be adopted within the scope of the claims.

In the drawing, Fig. 1 is a longitudinal View partly in section and partly in elevation, showing one modification of my invention as used in conjunction with the throttle of an internal combustion engine.

Fig. 2 is a view partly in plan and partly in section taken by the line in 2-2 in Fig. l.

Clarence B. Howard, in his Patent No. 2,096,745, has described a frictionally rotated switch having a rotating member which is clutched to a shaft and limited in its arc of rotation in either direction. Make and break means are operated by the frictionally rotated member, the stationary contacts being resilient in order that pressure be applied between the stationary and moving con tacts during their entire engagement.

The invention herein to be described claimed is in the nature of an improvement on the Howard switch, and a simplification thereof, in that I use only a single resilient member for supplying contact pressure and for supplying frictional forces in the clutch, whereas Howard utilizes separate resilient members for these purposes.

While I will describe my switch as app-lied to a butterfly valve shaft, forming part of the throttle mechanism in an internal combustion engine, it will be appreciated by those skilled in the art, that this is merely one preferred use and that other uses will be fully met by the appended claims.

Referring directly to the drawing for a more detailed description of my invention as exemplified by the modifications shown therein, in Fig ure 1, intake manifold l of an internal combustion engine is provided with the usual butterfly valve shaft 2, connected to a butterfly valve 3, within the manifold.

Inasmuch as it greatly simplifies the construction and reduces the expense, I prefer to mount the switch of my invention directly upon the 5 butterfly shaft 2, as described and claimed by Howard in his application Serial No. 124,863, filed Feb. 9, 1937, which became Patent No. 2,153,621 on April 11, 1939 although it must be fully realized that a separate shaft may be uti lized if desired whenever the switch is to be used in this position, or for other purposes. Mounted on shaft 2 is a contact member 5 freely movable thereon both rotationally and longitudinally. The fit of this member 5 to the shaft need not be 15 a close one, sufficient clearance being given so that the contact member does not bind thereon. A case 6 is provided through which shaft 2 enters in an axial position. This case is preferably open at the end away from. the manifold, and is stabilized and kept from rotating by a case bracket 1 attached to the case and to the manifold or any other convenient stationary object. Within the case at the manifold end thereof is positioned a sleeve 8, solidly pinned to the shaft 2, and having 25 a clutch face 9.

An intermediate link l0, preferably hollow and cylindrical, has a link clutch face lil bearing against sleeve clutch face 9, the two faces forming a friction clutch. The opposite end of link Ill is formed with projections I I entering recesses I2 in contact member 5, so that link ID will rotate with contact member 5, but at the same time contact member 5 is free to move longitudinally away from link it). An end plate It, preferably of insulated material, closes the case and stationary contacts l4 extend through the end plate to terminate in contact faces 15 which bear against contact member 5. These contact faces l5 are preferably raised above the level of end plate l2 and form stops which limit longitudinal movement of contact member 5 outward along shaft 2. The contact faces are preferably rounded to reduce friction.

On the outer face of contact member 5 is posi-- tioned a conductive area [6, preferably segmental, slightly more than degrees of arc and positioned with respect to the stationary contacts M, so that it will bridge them in one rotational position, but will not bridge them in another. Thus, at a certain point of rotation of the contact member 5, contacts [4 are connected through segmental area IE, and disconnected at another position.

Clutch pressure between faces 9 and I0 and contact pressure between member 5 and stationary contacts I4 is supplied by a single spring I! preferably positioned around shaft 2 and within hollow link Ill.

The proper arc of rotation of member 5 to include both make andbreak of an electric circuit across contacts I4 is limited by means of a stop arm l8, projecting from link l and positioned in the path of stops l9 extending from a stop bracket 2|] fastened inside the case.

An external circuit, such as, for example, a "sloW light circuit including a power source 2! and a slow lamp 22 may be bridged across contacts l4, although other circuits will occur to those skilled in the art when the switch is used for other purposes.

In operation, when shaft is rotated by the usual throttle shaft 2 of the engine, contact member 5 will be frictionally rotated in the direction of the rotation of shaft 2 through the medium of the friction between clutch faces 9 and Ml, this friction being developed by spring ll, until the link IQ and connected contact member 5 can no longer rotate because of limitation of stops i9. Shaft 2, however, may'continue to rotate in the same direction inasmuch as the clutch will then slip. Upon any reversal of rotation of shaft 2, link Hi, consequently, contact member 5, will im mediately be rotated in the opposite direction until the opposite stop 19 prevents further rotation of the contact member without, however, interfering in any way with further rotation of shaft 2. Thus, by proper arrangement of contacts l4 and conductive area It, I am able to make and break electric circuit in accordance with the direction of rotation of shaft 2, irrespective of amount of rotation of shaft 2 be-- yond the minimum amount necessary to open and close the circuit.

I prefer to arrange the segmental areas it and contacts [4 so that when the throttle is being closed from any open position, the circuit will be made through the switch to light lamp 22 and when the throttle is being opened from any closed position, the circuit will be broken through lamp Z2, thereby giving, when the internal combustion engine is being used in an automotive vehicle, a signal signifying that deceleration of the vehicle is about to occur due to power withdrawal. Such signals are known as slow signals.

In the entire operation of the device, positive contact is made between the stationary contacts I l and conductive area by virtue of the spring I! which acts both as a clutch spring and as a spring forcing the contacts together. Thus, there will always be a positive contact and a positive clutch action with a minimum of parts in the switch.

It will be obvious from an examination of the switch herein described that the switch of my invention is not limited to controlling a single circuit and that different arrangements of stationary contacts and rotating areas may be combined to give circuit connections as may be desider for any specific purpose. The main feature of my present invention therefore, vis the use of a resilient member supplying both clutch pressure and a positive contact pressure. It should also be noted that I have distributed stationary contacts l4 in opposite locations on end plate l2, so that no tilting or binding of isk or member 5 will take place and it is obviou that if desired, more points of support may be provided in case delicate balancing of pressures is necessary in any particular form of switch.

I claim: 1. A frictionally driven switch comprising a shaft, a member freely rotatable and slidable on said shaft, a conductive area on one face of said member, a stationary contact in the path of rotation of said area, means for limiting rotation of said member to an arc, including connection and disconnection of said area with said contact, a disc surface positively rotated by said shaft,

and having a disc clutch surface thereon, a link mounted on said shaft free to move'longitudinally thereon and rotatably interlocked with said member, said link having a link clutch surface thereon contacting said disc clutch surface, and a spring between said link and said member simultaneously urging said clutch faces together, and said member against said stationary contact in opposite directions.

2. A switch in accordance with claim 1, wherein the said link has arms entering recesses in said member and wherein said resilient member is a coil spring positioned around said shaft to urge said member and said link apart against said contact and said positively rotated surface respectively in opposite directions.

3. A frictionally driven switch comprising a shaft, 2. driving disc positively rotated by said shaft, a link disc mounted on said shaft and free to rotate and move longitudinally thereon, said discs having opposed surfaces contacting to form a friction clutch, arms on said link disc extending away from said discs parallel to said shaft, a switch disc mounted on said shaft and free to rotate and move longitudinally thereon, said switch disc having recesses therein engaging the ends of said arms, a conductive area; on the end face of said switch disc, a stationary contact positioned in the path of rotation of said area and limiting the longitudinal movement of said switch disc in a direction away from said link disc, a resilient member postioned to urge sad link disc and said switch disc apart to simultaneously supply clutch and contact pressure, and stop means for limiting the rotation of said link and switch discs to an are including connection and disconnection of said area with said stationary contact.

4. Apparatus in accordancev with claim 3, wherein the resilient member is a coil spring positioned around said shaft and between said arms and shaft shaft.

5. Apparatus in accordance with claim 3, wherein a plurality of stationary contacts are provided positioned in opposition to longitudinal movement of said switch disc and spaced around said shaft to maintain equal pressure thereon as said switch disc rotates to prevent binding thereof on said shaft.

HERBERT E. METCAI rF. 

